STMicroelectronics L7983PU33R

Overview

L7983PU33R from STMicroelectronics is a 3.3 V fixed-output, 300 mA synchronous step-down DC-DC regulator with peak current mode control, operating from 3.5 V to 60 V input. It features dynamic Low Consumption Mode (LCM) and Low Noise Mode (LNM) selection, 10 µA quiescent current at VIN > 24 V in LCM, and integrated soft-start, OVP, thermal shutdown, and output sequencing via open-drain RST. Used in industrial 24 V/48 V bus systems requiring ultra-low standby power and low-noise operation.

For engineers reviewing the L7983PU33R datasheet, L7983PU33R pinout, L7983PU33R application, or L7983PU33R equivalent, key selection criteria include its 3.3 V fixed output accuracy (±1%), programmable 200–2.2 MHz switching frequency, dual-mode LCM/LNM transition timing (14 µs), internal compensation, and VIN-compatible EN/UVLO with adjustable threshold - all critical for fail-safe sensor nodes and battery-powered edge devices.

Technical Context

The L7983PU33R implements a peak current mode, constant-frequency buck architecture with integrated high-side P-MOSFET and low-side N-MOSFET, anti-shoot-through logic, and adaptive dead-time control. Its internal trans-conductor (gm) error amplifier and slope-compensated PWM comparator enable stable regulation without external compensation components.

Mode selection is hardware-driven via the LNM/LCM pin: LCM enables pulse-skipping for <10 µA IQ at light load, while LNM enforces fixed-frequency operation with reverse-inductor-current capability for <10 mVpp output ripple. Synchronization to external clock (180–2400 kHz) and spread-spectrum dithering further reduce EMI in noise-sensitive applications.

Key Specifications

Pinout & Package

Package: PowerSSO-10 (exposed pad), thermally enhanced 3 mm × 3 mm, 0.65 mm pitch, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck regulator applications.

Compared with TPS54202DRCT and MAX17504ATP+T, the L7983PU33R uniquely combines 48 V bus compatibility, sub-10 µA quiescent current, hardware-dynamic LCM/LNM switching, and integrated RST sequencing - making it optimal for space-constrained, battery-backed, or safety-critical 3.3 V point-of-load applications where both efficiency and noise control are non-negotiable.

Availability

L7983PU33R is available at Aetrix Electronics and suitable for industrial sensor nodes, fail-safe PLC modules, decentralized edge AI devices, and low-noise analog signal chains requiring stable component supply across long production lifecycles.

Supply support for L7983PU33R includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, microcontrollers, and automotive-grade ICs with broad industrial certification coverage.

The L7983 series is part of ST's high-voltage synchronous buck regulator product line, engineered specifically for robust, low-power operation in harsh industrial environments - emphasizing ultra-low IQ, wide VIN range, and integrated fault protection for decentralized intelligent nodes.

FAQ

What is the minimum input voltage required for L7983PU33R to regulate 3.3 V output?

The L7983PU33R requires a minimum input voltage of 3.5 V to maintain regulation at 3.3 V output. Below this, the internal UVLO circuit disables switching to prevent unstable operation. The device guarantees full functionality down to 3.5 V even at maximum load and temperature extremes, per DS13354 absolute maximum ratings.

Can the L7983PU33R be synchronized to an external clock while operating in Low Consumption Mode?

No - external clock synchronization is only active when the LNM/LCM pin is driven high (LNM mode) or receives a valid clock signal (180–2400 kHz). In LCM mode (pin low), the device operates in free-running pulse-skipping mode and ignores external clock inputs. Synchronization is disabled during LCM to preserve ultra-low quiescent current behavior.

How does the RST pin behave during output voltage pre-bias conditions?

During pre-bias (VOUT > 0 before startup), the L7983PU33R disables sinking capability on the RST pin until soft-start completes. RST remains high-impedance until VOUT reaches ≥90% of 3.3 V, then releases after the 2.0 ms delay. This prevents false resets and ensures safe power-up even when output capacitors are pre-charged from another source.

Is an external bootstrap capacitor required for the high-side MOSFET drive?

No - the L7983PU33R integrates a charge-pump-based high-side gate driver that self-generates the required floating bias voltage. No external bootstrap capacitor or diode is needed, simplifying layout and reducing component count. This is confirmed in the block diagram (Figure 2) and "Power section" description in Section 5.1 of DS13354.